[Task]: Replace the term `master`

### What would you like to happen?

In support of #22777, the output of this task is to replace the use of the term `master` in this repository, namely:

- Rename the `master` branch to `main`
- Rename references to the `master` branch to `main` in the code, for example [here](https://github.com/apache/beam/blob/121597351d89ffe980907516f1f95f0d6a8afa49/sdks/python/container/license_scripts/dep_urls_py.yaml#L35)
- Rename, where possible, code using the term `master` that does not reference the `master` branch i.e. [`master_url`](https://github.com/apache/beam/blob/f68ae5ff467c2a52f49aacd8f357aa210ec80354/sdks/python/apache_beam/runners/interactive/interactive_beam_test.py#L46)
- Create a gradle task that automates checking with exclusions the repository and pull requests for uses of the term `master`.

As of this writing, a [search on the term master](https://github.com/apache/beam/search?q=master) yields 381 results. Some terms may not be replaceable due to a dependency on a technology that also uses the non-inclusive term. There may be other non-inclusive terminology in the repository

The [Inclusive Naming Initiative](https://inclusivenaming.org/) lists `master` on its [Tier 1 Word List](https://inclusivenaming.org/word-lists/tier-1/_master/), recommending `main` as a candidate replacement, to be adopted immediately. Other organizations and communities support and promote awareness of inclusive language in technology.

- [Internet Engineering task Force](https://datatracker.ietf.org/doc/draft-knodel-terminology/)
- [Academy Software Foundation](https://www.aswf.io/blog/inclusive-language/)
- [Apache Airflow project](https://github.com/apache/airflow/issues/12982)
- https://sfconservancy.org/news/2020/jun/23/gitbranchname/

### Issue Priority

Priority: 2

### Issue Component

Component: beam-community